Dell Precision 330 - Manual (Page 24)

Removing a Drive Bracket (Mini Tower Chassis)
6. Remove the drive from the bracket.
Turn the drive/bracket assembly upside down and remove the four screws that secure the drive to the bracket (see the following figure).
Removing the Drive from the Bracket
Replacing a CD, Zip, or Other Externally Accessible Drive (Mini Tower Chassis)
1. Attach the new drive to the drive bracket.
Turn the drive upside down, and fit the bracket on the drive so that the screw holes align. To ensure proper installation, all screw holes should be aligned and the
tabs on the front of the bracket should be flush with the front of the drive (see "
Removing the Drive from the Bracket ").
To further ensure proper positioning of the drive in the chassis, insert and tighten all four screws in the order in which the holes are numbered (the holes are
marked "1" through "4").